Ion: Let’s see. I am going to say Siegecrafter Blackfuse… I think the last few bosses, Siegecrafter Blackfuse, Paragons of the Klaxxi and of course Garrosh, befitting their place near the end of the instance, are all going to have some very significant challenges that they pose. Obviously all the bosses are difficult but these world class guilds that have been practicing on the PTR and are taking every possible advantage, they’re going to progress through the rest of the zone at roughly the same rate that they progressed through Throne of Thunder.

If Ion's predictions hold true then we can expect to see guilds slow up when they get to heroic Siegecrafter Blackfuse, the third last boss in the new raid.